The present invention relates to electrolytic capacitors and electrolytes used in such capacitors, and, more particularly, to electrolytes and capacitors having increased stability over wide temperature ranges.
There has been a continuing search for electrolyte systems that exhibit little or no resistivity changes at high temperatures (105.degree.-125.degree. C.). One of the properties related to a capacitor's useful life expectancy is its effective series resistance (ESR) stability.
Over the years, several different formulations have been proposed for use in electrolytic capacitors. For example, U.S. Pat. No. 4,652,968 to Shimamoto et al. discloses a non-aqueous electrolyte with reported increased stability at low and high temperatures. The disclosed electrolyte includes a diazobicyclealkenes as a solute.
U.S. Pat. No. 3,539,614 to Ross et al. discloses an electrolyte for use in capacitors which includes n,n-dimethylformamide (DMF) together with quaternary ammonium salts such as tetramethyl borodisalicylate.
U.S. Pat. Nos. 4,578,204 to Anderson, and 4,541,037 to Ross et al. employ phosphoric acid in capacitor electrolytes in relatively small quantities.